The present invention relates to a fuel injector.
Japanese Registered Utility Model 63-133260 describes a fuel injector which is distinguished by the presence of several injection orifices in a valve-seat member. Swirl grooves are provided in an inner wall, through which fuel which flows in through feed lines is injected with a swirl. This permits more rapid atomization of the fuel and improved atomization and mixing performance, while the adhesion of fuel to the injection hole walls is reduced, so that the concentration of hydrocarbons in the exhaust gas may be lowered.
German Patent Application 41 31 499 describes a fuel injector which is provided with four swirl channels in a swirl section outside of a sealing surface. The channels discharge into an injection channel at a lateral distance from a longitudinal valve axis.
One disadvantage in the conventional fuel injectors described above is in particular the incomplete generation of swirl, which does not extend to all of the fuel, since part of it flows through the injection holes parallel to the axis. That causes uncontrollable divergences in the shape and the apex angle of the conical mixture cloud, leading to incomplete combustion.
German patent Application No. 198 04 463 describes a fuel injection system having an injection nozzle which injects fuel into a combustion chamber formed by a piston and cylinder assembly and provided with a spark plug which extends into the combustion chamber. The injection nozzle has at least one row of injection holes, distributed around the circumference of the injection nozzle. By aiming the injection of fuel through the injection holes, jet-controlled combustion behavior is implemented by forming a mixture cloud having at least one jet which is directed in the direction of the spark plug to ignite, and having additional jets which form a mixture cloud which is at least approximately closed, i.e., contiguous.
A fuel injector according to an example embodiment of the present invention has the advantage that the swirl is generated even as the fuel flows to the injection openings and may be further reinforced and homogenized by the swirl grooves which extend into the injection orifices. The swirl grooves in the face of the valve-seat member are designed so that they are as nearly perpendicular to a center line of the respective injection orifice.
The design of the fuel injector according to the example embodiment of the present invention allows the advantages of a multiple-orifice fuel injector to be combined with those of an injector having swirl conditioning, so that the respective disadvantages of the individual designs may be eliminated.
It may be advantageous that, in the example embodiment, the swirl grooves discharge into the injection orifices at any angle desired relative for example to a circumferential direction of the fuel injector but open into the injection orifices perpendicular to the center line of the injection orifices. This enables the orientation to be adapted for various types of fuel infeed.
The number of injection orifices and of the corresponding swirl grooves may be chosen freely and may be adapted easily to the fuel injector.